1. Field of the Invention
The present invention relates to a method for controlling the temperature of a substrate within a short period of time, a thermal processing device for heating or cooling a substrate, and a device for supporting a substrate.
2. Description of the Related Art
Devices which are used for processing substrates such as semiconductor wafers and glass substrates for liquid crystal displays often include a hot plate oven for heating the substrate, a chill plate for cooling the substrate, and a spinner for coating the surfaces of the substrate with a processing fluid or for cleaning the surfaces of the substrate.
The structure and temperature control process of a conventional hot plate oven will now be described.
The conventional hot plate oven used in these devices includes a substrate supporting plate for supporting the substrate, and a heat source such as a mica heater for heating the substrate supporting plate. The temperature of the substrate supporting plate is brought to a predetermined substrate processing temperature (for instance, 110.degree. C.) by means of a controller. When a substrate at, for example, room temperature is mounted on the substrate supporting plate, the temperature of the substrate supporting plate is lowered rapidly. The substrate is then heated to the above-described substrate processing temperature by the heat source, and is thermally processed for a predetermined time period.
Here, the conventional mica heater only has a temperature increasing function. As a result, when the temperature of the substrate is brought up to the substrate processing temperature, the temperature of the substrate supporting plate is raised rapidly to a temperature close to the selected substrate processing temperature, and then is asymptotically increased until that temperature is reached.
This conventional temperature control method of bringing the substrate supporting plate up to the desired temperature takes a considerable amount of time. In addition, if the temperature of the substrate supporting plate exceeds the desired temperature, a considerable amount of time is required in order to lower this temperature to the desired level.
In addition, because the temperature increasing characteristics cannot be control precisely, the amount of time it takes the temperature to reach the desired level cannot be controlled. As a result, thermal progress cannot be controlled, and the substrate may be given an excessively large quantity or an excessively small quantity of heat.